Jan Kuciak had been investigating the suspect's business activities when he and his fiancee, Martina Kusnirova, were shot dead last year. The murders sparked massive protests and prompted the prime minister to resign.

A man has been charged with ordering the killings of investigative journalist Jan Kuciak and his fiancee, Martina Kusnirova, last year, Slovakian authorities announced on Thursday.

Special prosecutors identified the suspect as Marian K., withholding his last name as is standard practice in Slovakia, adding that they believe the contract killing was tied to Kuciak's investigative work.

"The motive for the murder was Kuciak's work as a journalist. The investigator (has based the charge) on objective evidence that can't be specified at the moment," one of the prosecutors said.

Slovaks pay tribute to murdered journalist Jan Kuciak

Thousands pay tribute

Around 20,000 Slovaks have rallied in the capital, Bratislava, in sub-zero temperatures for murdered investigative journalist Jan Kuciak and his girlfriend, Martina Kusnirova. Their deaths have shaken the country and led to calls for the government of Prime Minister Robert Fico to bring the killers to justice.

Slovaks pay tribute to murdered journalist Jan Kuciak

'An attack on all of us'

Marching behind a banner saying "An attack on journalists = an attack on all of us," many people walked in silence, holding candles. Others held up photographs of the two victims, both 27, who were shot dead in their Bratislava home in last weekend.

Slovaks pay tribute to murdered journalist Jan Kuciak

First documented journalist death

Kuciak was the first journalist to be killed in Slovakia, according to Reporters Without Borders. He was about to publish an article exposing alleged links between the Italian mafia and businessmen operating in eastern Slovakia. His unfinished investigation was published posthumously on Wednesday.

Slovaks pay tribute to murdered journalist Jan Kuciak

Political pressure

Slovak police on Thursday detained several Italian businessmen named by Kuciak in his report, which contained allegations of abuse of EU subsidies and other fraud. One man mentioned in the article had alleged ties to people working for the prime minister. The case has put mounting pressure on Fico, with some protesters calling for his government to resign.

Slovaks pay tribute to murdered journalist Jan Kuciak

Solidarity across Europe

Similar marches were also held in more than 20 other Slovak cities, as well as in London, Paris and Brussels. Above, people light candles in memory of Kuciak in front of the Slovak embassy in the Czech capital, Prague.

Slovaks pay tribute to murdered journalist Jan Kuciak

Call for change

Kuciak's death has fueled public anger over media freedom and graft in Slovakia. Transparency International ranks the country as the seventh most corrupt EU member. "We live in a mafia state," student Jan Kubis told AFP. "They were not much older than I am. Something must change in Slovakia."

Slovaks pay tribute to murdered journalist Jan Kuciak

Tragic end

Kuciak and his girlfriend, Martina Kusnirova, had planned to get married in May. Kusnirova was laid to rest in her wedding gown during a ceremony on Friday in the northern Slovak town of Gregorovce. Kuciak's funeral will be held on Saturday in Stiavnik, near the Czech border.